Summary
A differential oxygen sensor using the paramagnetic principle in a pneumatic bridge configuration has been constructed and tested. The signal being picked up with a differential pressure transducer is generated in a measuring cell with a strong magnetic field being switched on and off with a frequency of 110 Hz. The output signals is a DC-voltage proportional to the O2 concentration difference between the two gases to be measured. A response time of 130 ms has been obtained.
A special emphasis on the mechanical design was put to minimize the internal magneto-mechanical noise and to attenuate the external pressure and vibration interference. To eliminate the relatively strong temperature dependence of the paramagnetic effect a compensation circuit was designed as an integral part of the sensor.
In performance investigations linearity, stability, noise, humidity and pressure effects as well as sensitivity for other gases were studied.
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Meriläinen, P.T. A fast differential paramagnetic O2-sensor. J Clin Monit Comput 5, 187–195 (1988). https://doi.org/10.1007/BF02933716
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DOI: https://doi.org/10.1007/BF02933716